Power tools of this kind, as hand-held tools in the form of cordless screwdrivers, are known from German Patent Application Publication DE 10 2004 058 809 A1. In these tools, a tool receptacle is driven via a multi-stage planetary drive. Provided in the transition to the tool receptacle is a torque limiting unit by which the power flow between motor and tool receptacle is interrupted if the torque being transferred exceeds a predefined set value. The torque limiting unit operates in locking fashion with the aid of a spring brace that, in normal operation, immobilizes the planet carrier of the planetary drive in a rotational position with respect to the housing. Only if the torque to be transferred to the tool receptacle exceeds a set limit value is the planet carrier disengaged, and the power flow to the tool receptacle thereby interrupted.
With this known approach, the locking brace extends in surrounding fashion with respect to the planetary drive, and spring bracing is accomplished with the aid of helical springs that in turn are braced fixedly with respect to the housing and impinge axially, in the transition to a radially protruding edge of the planet carrier, on mutually contiguous locking disks that are fastened nonrotatably and in locking fashion with respect to one another as long as the limit value predefined as a maximum value for the torque is not exceeded. If the limit value is exceeded, the locking connection between the locking disks is then abolished by an axial offset thereof, and torque transfer to the tool receptacle is interrupted. Overall, this kind of arrangement of the locking receptacle, with a surrounding placement with respect to the planetary drive and axial coverage thereof, yields an enclosed configuration for the torque limiting unit, but also a configuration of the power tool that limits its scope of use.
According to a further known approach, the torque limiting unit works with a spring brace, located axially with respect to the ring gear of the planetary drive, by which the locking elements are pushed in locking fashion against an end face of the ring gear.